As a conventional camera module, a camera module is described in JP 2001-78213 A. FIG. 47 is a sectional view showing a configuration of the camera module described in JP 2001-78213 A.
In FIG. 47, an imaging system 9010 is an optical processing system that directs light from an object through a diaphragm 9110 and an imaging lens 9100 and forms an image on an imaging surface of an imaging device 9120. The diaphragm 9110 has three circular apertures 9110a, 9110b and 9110c. Light from the object that has left the apertures 9110a, 9110b and 9110c respectively and entered an incident surface 9100e of the imaging lens 9100 leaves three lens portions 9100a, 9100b and 9100c of the imaging lens 9100 and then forms three object images on the imaging surface of the imaging device 9120.
A shielding film is formed on a flat portion 9100d of an outgoing surface of the imaging lens 9100. On the incident surface 9100e of the imaging lens 9100, three optical filters 9052a, 9052b and 9052c transmitting light in different wavelength ranges are formed. Further, in the imaging device 9120, three optical filters 9053a, 9053b and 9053c transmitting light in different wavelength ranges also are formed on three imaging regions 9120a, 9120b and 9120c corresponding to the three lens portions 9100a, 9100b and 9100c of the imaging lens 9100, respectively.
The optical filter 9052a and the optical filter 9053a have spectral transmittance characteristics mainly transmitting green (indicated by G), the optical filter 9052b and the optical filter 9053b have spectral transmittance characteristics mainly transmitting red (indicated by R), and further the optical filter 9052c and the optical filter 9053c have spectral transmittance characteristics mainly transmitting blue (indicated by B). Accordingly, the imaging region 9120a is sensitive to green light (G), the imaging region 9120b is sensitive to red light (R), and the imaging region 9120c is sensitive to blue light (B).
In such a camera module with a plurality of imaging lenses, when the distance from the camera module to an object (a subject) varies, the space between a plurality of object images that are formed on the imaging surface of the imaging device 9120 respectively by the plurality of imaging lenses also varies.
In the camera module described in JP 2001-78213 A, the space between optical axes of a plurality of image forming systems is set such that the difference between the space between a plurality of object images when the object is present at a virtual subject distance D [m] and the space between a plurality of object images when the object is present at an infinite distance is smaller than twice the pixel pitch of a reference image signal, where the virtual subject distance D [m] is defined as D=1.4/(tan(θ/2)) as a function of shooting angles of view θ [°] of the plurality of image forming systems. In other words, in the camera module described in JP 2001-78213 A, since the space between the optical axes is set such that the difference between both the spaces between the respective object images on the imaging surface is smaller than twice the pixel pitch of the reference signal even when the same image processing as that optimized for shooting an object present at the virtual subject distance D [m] is performed for the shooting of an object present at an infinite distance, it is possible to suppress a color shifting of the image of the object at an infinite distance to an allowable level.
In recent years, portable equipment such as camera-equipped mobile phones has become widespread. Accompanying the reduction in size and thickness and the improvement in performance of such portable equipment, there has been a demand for smaller and thinner camera modules with a higher performance. For example, these camera modules are required to have an automatic focusing control function and be capable of not only a landscape shot (shooting an object at a substantially infinite distance) and a portrait shot (shooting an object usually at a distance of several meters) but also a macro shot (shooting an object at a distance of several centimeters to several tens of centimeters).
In the camera module described in JP 2001-78213 A, the thickness is reduced by providing a plurality of the lens portions 9100a, 9100b and 9100c. However, this conventional camera module has no automatic focusing control function. Also, the virtual subject distance D [m] is set with portrait shots in mind. Therefore, although this conventional camera module can deal with landscape shots and portrait shots, it cannot deal with macro shots.
As another conventional camera module for solving the problem that has not been solved by the camera module described in JP 2001-78213 A, a camera module is described in JP 2002-330332 A. FIG. 48 shows an exemplary image taken by the camera module described in JP 2002-330332 A and its divided sub-regions. In the taken image, a central portion k0 and detection regions k1, k2, k3 and k4 surrounding the central portion k0 are formed. Then, parallaxes p0, p1, p2, p3 and p4 of the respective detection regions are calculated. From these parallaxes, the one in a predetermined range is extracted. If there are a plurality of parallaxes to be selected, the one in the region closer to the center is selected. Furthermore, using the selected parallax, the entire taken image is corrected.
In the conventional camera module described in JP 2002-330332 A, the taken image partially is formed into a plurality of sub-regions, the parallaxes of these sub-regions are calculated, one parallax is selected from them, and the entire taken image is corrected based on this selected parallax. For example, in the case where there are both a person M at a distance of about 2 m from the camera at the center and a person N at a distance of about 10 m on the edge of the taken image as shown in FIG. 48, the person M located at the center of the taken image is considered as a subject, and the entire taken image is corrected based on the parallax p0 in this region k0. At this time, since the parallax of the person M is the same as the selected parallax p0, the parallactic influence can be corrected, resulting in a beautiful image in the region of the person M. However, since the parallax of the person N is different from the selected parallax p0, the parallactic influence cannot be corrected. Therefore, color irregularities are generated in the region of the person N, so that a beautiful image cannot be obtained.